1. Field of the Invention
The present invention relates to injection molding, and more particularly to a method of and apparatus for automatically controlling the length of a row of articles, such as slide fastener coupling elements, to be injection-molded on a multi-cavity mold.
2. Prior Art
In the manufacture of slide fasteners, it is known that a row of coupling elements is injection-molded on one longitudinal edge of a fastener stringer tape placed between a pair of mold halves jointly defining an elongate runner and a plurality of successive cavities spaced at equal intervals along the runner. To this end, various slide fasteners of different lengths require a plurality of multi-cavity molds each having a succession of cavities of a different row length. A suitable one of the molds must be chosen, depending on the length of a row of coupling elements to be molded, which is laborious and time-consuming. The same problem has been experienced in the production of a series of other thermoplastic articles.